Connections/threads are the same. If its 2 connections thats like having 2 browser tabs open loading 2 different pages at the same time. 100 connections is 100 browser tabs open at the same time loading different pages.

The following 1 user says Thank You to loopline for this post:1 user says Thank You to loopline for this post • olavor

yes, proxies get use either randomly or in rotation, depending on the feature. but yes its more or less distributed evenly, or mostly evenly, its a bit random on purpose.

Generally yes your on point with your 2 connections per proxy, but its not cut and dry. Some domains are aggressive and ban really fast, like even at 2 connections. Most domains 2-3 connections are fine, and like wikipedia you can hammer all day at 7 connections or more and they won't ban you. So it just depends.

Cool. That clarifies.
I'm running broken links checker with several urls of a same website at once.
For some urls I do get results and for others I get error.
I'm using 10 proxies and 20 connections.
Is there any way I can find which of the proxies is being blocked so that I remove it from the list?
I know I could try running one by one, but was wondering if there's a better way.
That would be important when using a lot of proxies.